Devil face tumour disease is a condition found in tasmanian devils, it is one of only two examples of a transmissable cancer (it can be passed on to other individuals), the other is a sexual cancer in dogs Can someone add to this part, please?. Tumours develop around the face, throat, eyes, mouth, and even into the brain, this condition is fatal if the brain is given too much pressure or if their throat is closed, leading to asphyxiation.
The reason why this cancer is transmissable is because the tasmanian devils' DNA are all very similar to each other, so cancerous cells from another individual is not recognized, and therefore rejected, by the immune system. The reason why it develops around the head and neck areas as these cancerous sells may be picked up by feeding on a corpse that has already been fed on by an already infected devil, or if a healthy individual scraps with an infected individual, which involves mainly their jaws.
It is suggested that this disease started when one tasmanian devil had developed cancer around its head, and passed it on from there through the scenarios mentioned above.